In article <
[email protected]>,
John Kane <
[email protected]> wrote:
>A slightly more honest version can be seen at
>http://ca.geocities.com/jrkrideau/cycling/times.stats.pdf however
>scale makes some of the results look actually less than zero.
Another problem with the Times's graph which you haven't corrected is
that the three different ways of comparing - per journey, per km and
per hour - are presented with arbitrary relative scaling on the same
graph. The magnitude axis isn't in the same units for each comparison
method, although expressing it as `per 100,000' obscures this.
Furthermore, the choice of specific units and scales causes the `per
hours' and `per journey' graphs to use more of the available space.
The effect is as if there were `more' deaths `per hour' than `per km',
which is obviously nonsense - but it leads the eye to think that these
numbers are the really serious and important ones.
A fairer representation would be something like this:
per km per journey per hour
Bus/coach | | |
Car |= |= |
Foot |#####= |= |
Pedal Cycle |##### |#= |
Motorcycle |############### |############### |###############
0 5 0 1 0 3
deaths/ 100M km /1M journeys /1M hours
The inclusion of motorcycles which are far more dangerous by all
measures completely obscures the coomparisons. Without motorcycles
you get this:
per km per journey per hour
Bus/coach | |= |
Car |# |#### |####
Foot |############### |#### |######
Pedal Cycle |############## |############### |###############
0 1 2 0 1 2 3 0 1 2 3
deaths/ 100M km /10M journeys /10M hours
Of course that still doesn't fairly represent the effect of cycling on
life expectancy because it neglects the health benefits and of course
`per journey' is a ridiculous approach anyway.
NB that you will obviously need a fixed-width font to make sense of
the above.
--
Ian Jackson personal email: <
[email protected]>
These opinions are my own.
http://www.chiark.greenend.org.uk/~ijackson/
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